PURPOSE: To enable a belt part to be easily engaged with a tightly binding part by forming a notch part from which the belt part can be inserted into a surround wall on theupper part of the surrounding wall for constituting the tightly binding part.

CONSTITUTION: A belt part 2 is inserted into surrounding wall 11 from a notch part 12 of a tightly binding part 1 after passing the belt part 2 around a linear article in order to bind the linear article, thereby a locking body 13 and a locking tooth 22 of the belt part 2 can be engaged with each other. After that, the belt part 2 is pulled in the arrow direction until it is not moved, thereby the binding is completed. Since the tightly binding part 1 and the belt part 2 are firmly engaged with each other by a protrusion 16 of the surround wall 11 and front side grooves 21 of the belt part 2, the belt part 2 is no longer detached from the notch part even if external force acts on the linear article. Moreover it is rarely detached if the external force to act on the linear article is not so large, even if there is no protrusion 16 nor groove 21. Accordingly, the belt part 2 can be easily engaged with the tightly binding part 1 in a short time even if the space of a workshop is small, or even if the inside of the workshop is dark.